The International Atomic Energy Agency has, under its Statute, specifically defined functions relating to radiation safety, in particular, responsibilities for the development of standards of safety and provision for their application. These functions are fulfilled through the development of a wide range of standards, including those on preparedness and response to nuclear accidents or radiological emergencies. It also devotes considerable effort to assisting countries in applying those standards. In addition, the Agency has responsibilities placed on it by virtue of a number of Conventions, two of which are relevant to nuclear accidents or radiological emergencies: the Convention on Early Notification of a Nuclear Accident (Early Notification Convention) and the Convention on Assistance in the Case of a Nuclear Accident or Radiological Emergency (Assistance Convention). Under the Assistance Convention, assistance may include medical response. This paper provides an overview of the Agency's work regarding emergency preparedness and response, with specific reference to a number of recent events. It also discusses new initiatives regarding the safety and security of radiation sources, which have, as a principal objective, the reduction of the risk of such events.